Tuyere



A. LAIST July 1, 1930.

TUYERE Filed Oct. 16, 1928 3 Sheets-Sheet 2 I/INVENTOR.

Lfllexanderbaz'si A TTORNEY A. LAIST July 1, 1930.

TUYERE Filed Oct. 16, 1928 I5 Sheets-Sheet 3 aowemcoz A 1. axe/v05? ,L/l/SZ Patented July .1 1930 June 11, 1928 and Patent No. 1,729,075, Sep- UNITED STATES ALEXANDER LAIST, .OF HELENA, MONTANA, ASSIGNOR TO ANACONDA GOPLPER MINING PATENT OFFICE COMPANY, A CORPORATION 01 MONTANA 'ruynnm Application filed October 16, 1928. Serial No. 312,770.

In previous application No. 284,462, filed tember 24, 1929,'I have described a slag blowing furnace with tuyeres near the bottom through which air and powdered coal are blown. The resent invention provides an improvement 1n tuyeres for this and other blowing furnaces.

' The accompanying drawings illustrate embodiments of the invention.

Figs. 1 and 2 are respectively section and plan of one type;

Figs. 3 and 4 are similar views of a seea vertical -ond type.

'Fig. 5 is a vertical section of the tuyres in connection withthe furnace and air and coal p y p pes.

The molt-en bath within the furnace 1 I stands above the tuyeres, three feet above in a specific case. The level of the molten slag is indicated at 15,Fig. 5. When the blowing engine stops the slag tends to run back into the tuyeres and the connecting pipes, burning any rubber hose connections and injuring valves; which means a shut down of. some hours before'starting again. Sometimes it is possible to tap the furnace immediately and save this repair work, but with the loss bf the charge. But not even this is possible in all cases. Where power to operate the blowing engine is taken from public lines particularly,

lightning storms and other causes'frequently cut 01f the power. With such installations it is particularly important to provide against back flow.

The present invention achieves practically perfect relief by maintaining the pressure in the mouth of the tuyere for a considerable time. If the power is restored promptly the blowing may be'resumed. If the delay is so great that there is danger of the 'charges freezing or working its way into the tuyere,=

the charge should be tapped-as soon'as necessary. c

The powdered coal (mixed with air) is fed through a chamber 2 undera considerable pressure, say a ninety pound air pressure. Additional air at a lower pressure, say sixteen pounds, is fed through a pipe 3 and the stream of mixed air and coal is thus fed through the tuyene-4 into the furnace.

In the pipe 3, closely adjacent to' the tuyere, is placed a check valve 5. Between the check valve and the furnace there is always a quantity of air under pressure. When the pressure fails at the source the automatic closing of the valve 5 leaves an air cushion in the tuyere. which gives the operator time to tap downwardly and forwardly and the check valve 8 is made a part of the fitting instead of using a standard globe valve 5 as in Fig. 1. Functionally the two designs are not substantially different. Various other arrangements may be adopted for securing the desired closure of a pocket of air under pressure.

4 Fig. 5 shows a powdered coal feed pipe 16 with branches 17 leading to the tuyere and operating with high pressure air, as above described; and a bustlepipe 18 supplying the low pressure air through branches 19. Each tuyre 4 carries a fitting, indicated as a whole, by the numeral 20, corresponding with the design of Fig. 1 or that of Fig. 3 and receiving a high pressure and powdered coal pipe 17 and a low pressure pipe 19. I In operating this type of furnace an interruption. of the pressure for thirty seconds would cause the slag to run into the air lines because of the depth of the moltencharge. above the tuyeres. It would take five or six hours to, clear the pipes and start again. The low pressure in the branches 19 drops to nothing within a few seconds after the power is out 01f. For the high pressure line,. a storage reservoir is possible and is gener ally used; but for the low pressure line such hi va reservoir would have to be so large as to be uneconomical.

Now when the power supplying the low pressure air is cut off, the check valve between the low pressure line and the tuyere closes and the tuyere is immediately filled with air at a conslderable pressure from the h pressure line. If we had not a check ve close to the tuyere or furnace in the low pressure line, the high pressure would force air back into the low pressure line from which it would leakout. The check valve thus confines the high pressure air and provides a cushion which prevents the slag from running into the tuyere.

Considering the liability of interruption of power supplied from electric service companies because of thunder and lightning storms, the saving involved in the provision of tuyeres of the improved type is extremely great and has proven so in practice.

The coal passes from the branch 2, Fig. 1, or 6, Fig. 3, downward into a mixing chamber 9 where it joins the air entering by the pipe 3, Fig. 1, or branch 7, Fig. 8, and is thence carried into the pipe 4. The usual slag overflow pipe 10 is secured in an opening at the lower part of the chamber 9 and is sealed therefrom by means of a flexible disc 11 held in place by'a bushing 12 as described in connection with my previous application above referred to.

Beyond the point of admission of the air supply, the casing has an end plate 13 through which there is an opening normally closed by a check valve 14 so that a poker or clearing bar can be introduced in case the tuyere is choked at its inner end.

It will be observed that in Fig. 3 the aircheck valve 8 is also hung so as to yield and permit the passage of such a poker.

The casing extends generally in a horizontal direction so as to be accessible for such clearing operations. The provision for poking out obstructions in the tuyere and for the escape of molten material therefrom makes it possible to keep the tuyere clear with a certain amount of trouble and delay.

The provision, however, of the check valve in the airline and the retention of a cushion of air in the tuyere make it possible to avoid the hard labor and delay involved in the use of the overflow and the poker opening except in extreme cases.

The present invention, therefore, adds greatly to the reliability and economy of the operation in eliminating to a large extent re- Eourse to the poker opening and the-over- What I claim is:

1. The combination with" a furnace for blowing air and fuel through a molten charge of a tuyere entering the furnace at a level substantially below that of the charge, a pipe leading to the tuyere, means including a age supply fails the valve will temporarily maintain a cushion of high pressure air between the pipes and the molten charge to hold the latter from flowing back-through the tuyere.

2. The combination with a furnace for blowing air and fuel through a molten charge of a tuyere entering the furnace at a level substantially below that of the charge, said tuyere having a rear valved opening through which a poker can be thrust to clear the tuyore, a source of supply of air under low pressure direct to the tuyere, a second source of supply of air under high. pressure to the tuyere including a storage means and means adjacent to the furnace for retaining temporarily a cushion of such high pressure air in the tuyere when the low pressure supply to the tuyere and the air supply to the high pressure storage means fails'and thus preventing back flow of the molten charge through the tuyere. i

3. The combination with a furnace for blowing air and fuel through a molten charge of a tuyere entering the furnace at a level substantially-below that of the charge, a hollow fitting communicating with the outer end of the tuyere, a pipe leading to said fitting at a point comparatively near. the furnace, means for supplying air under high pressure to said pipe, a second pipe leading to the fitting at a point comparatively remote from the furnace, means for supplying low pressure air to said second pipeand a check valve in the fitting between the points of connec tion to said plpes for retaining a cushion of the high pressure air in the fitting when the low pressure air fails and thus preventing back flow of the molten charge into the tuyere.

In witness whereof, I have hereunto signed my name. 

